Synthesis and crystal chemistry of the fast Li-ion conductor Li7La3Zr2O12 doped with Fe

Daniel Rettenwander, Charles A Geiger*, Georg Amthauer

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

Abstract

Nominal Li7La3Zr2O12 (LLZO) garnet, doped with 57Fe2O3, was synthesized by sintering oxides and carbonates at T = 1100 °C in air. X-ray powder diffraction measurements show that Li7–3xFe3+xLa3Zr2O12 with x = 0.19 crystallizes in the cubic space group Ia-3d, with a0 = 12.986(4) Å at room temperature. SEM and electron microprobe measurements were made to obtain compositional information and check for the presence of phases other than garnet. Inductively coupled plasma optical emission spectroscopy measurements were made to determine the Li content. 57Fe Mössbauer spectra obtained at 295 and 80 K show that about 96% of the total iron occurs as Fe3+ and 4% as Fe2+. Roughly two-thirds of the Fe3+ cations are assigned to the tetrahedral site (24d) and roughly one-quarter to a highly distorted site (possibly at 96h) in the garnet structure. Smaller amounts of Fe3+ and Fe2+, around 5% each, occur at other crystallographic sites. On the basis of published 27Al MAS NMR results and analysis of the 57Fe Mössbauer spectra, it appears that at low concentrations Al3+ and Fe3+ substitute in Li7La3Zr2O12 in a similar manner. The aliovalent substitution Al3+/Fe3+ ↔ 3Li+ in LLZO stabilizes the cubic phase and also probably promotes its high Li-ion conductivity.
Original languageEnglish
Pages (from-to)8005-8009
Number of pages5
JournalInorganic Chemistry
Volume52
Issue number14
DOIs
Publication statusPublished - 2013
Externally publishedYes

Fingerprint

Dive into the research topics of 'Synthesis and crystal chemistry of the fast Li-ion conductor Li7La3Zr2O12 doped with Fe'. Together they form a unique fingerprint.

Cite this